Austin Evers, the group's director, told NPR, "We can get a straight, factual answer in the courts, by asking an unspinnable question: Do you have records to support the president's tweets?"

Besides the tweet, Trump has talked about the wiretap claim, while FBI Director James Comey told the House Intelligence Committee in open session that his agency had "no information" about such alleged wiretaps. The lawsuit cites those public discussions to argue that the records are no longer classified.

American Oversight sued after the Justice Department rejected, and the FBI ignored, its Freedom of Information Act requests.

In a second case also filed Wednesday, American Oversight demands records in the evolving story of Russian interference in the presidential campaign. It seeks records on White House Chief of Staff Reince Priebus' communications with the FBI regarding Russian contacts with Trump associates and the campaign.

And it seeks Attorney General Jeff Sessions' list of foreign contacts, which he would have filed before his Senate confirmation hearing. That was the hearing where Sessions failed to recall meetings with the Russian ambassador to the U.S. The lawsuit says the list "would address a significant question regarding the integrity of a senior government official."

Asked for comment about either lawsuit, the White House referred NPR to the Justice Department.

Organized this winter, American Oversight is a group that includes former Obama administration lawyers and is using FOIA to monitor the performance and conduct of Trump administration agencies. Wednesday's lawsuits are the first, but Evers said more than 100 FOIA requests have been submitted.